1. Field of the Invention
The present invention relates to an improvement in or relating to a snorkel, more particularly to an improved snorkel which permits the adjusting of the exhaust amount from its valve to meet individual lung capacities, thereby permitting the simultaneous exhaust of the remaining water from the upper and lower ends of the tubular body of the snorkel.
2. Description of Related Art
One example of a conventional snorkel is disclosed in Japanese Utility Model (Hei) 6-10098(A). As shown in FIG. 9, it includes a valve mechanism 3 comprising a valve body (exhaust valve seat) 30 fixed to the water-exhaust bottom opening 1b of the snorkel tubular body 1, an associated flexible, pressure-sensitive element or water-exhaust valve 33 which is permitted to be deformed in cooperation with the valve body 30 for closing or opening, and a valve closure 6 positioned apart from the pressure-sensitive element 33. The water-exhaust valve 33 has a center post 7 defining two semi-openings 8 and 9 in the water-exhaust bottom opening, and the valve closure 6 has two apertures 6a and 6b facing the two semi-openings 8 and 9.
The valve closure 6 has the effect of preventing sand and other foreign substance from entering into the tubular body of the snorkel 1. The sub-opening areas 8 and 9 cannot be controlled so as to meet individual blowing strengths or individual lung capacities. If the blowing strength is weak, water will be exhausted slowly, and then the water-exhaust valve 33 will be deformed against external water pressure Q to blow remaining water off from the semi-openings 8 and 9, allowing leakage of air from the bottom end of the tubular body. Accordingly the air pressure available for exhausting water from the top opening or air-inlet of the tubular body is reduced, thereby making it difficult to exhaust water from the top opening or air-inlet of the tubular body.
Conversely, if the blowing strength is strong, water will be exhausted from the top opening or air-inlet of the tubular body, but water is allowed to remain on the lower end, and water drops fall from the inside wall of the tubular body on the bottom-remaining water until the water level rises above the permissible limit, sometimes upto the mouth piece.
Ideally the water which remains in the tubular body 1, the mouth piece 2 and the water-exhaust valve mechanism 3 is blown off from the top opening or air-inlet "A" of the tubular body, and at the same time, is exhausted from the bottom opening "B" by lowering the pressure-sensitive element 33, as seen from FIG. 8. The ideal condition in which water and air is exhausted from the top and bottom openings "A" and "B" simultaneously cannot be provided unless the snorkel meets a person's lung capacity.
As the top opening or air-inlet of the tubular body is exposed to the surrounding air, the pressure and impedance against which water and air are exhausted from the top opening or air-inlet of the tubular body is of a small value. The bottom opening of the tubular body is immersed in the water, and the pressure and impedance against which water and air are exhausted from the bottom opening is of a large value because of the adverse effects caused by the viscosity of surrounding water and by the water pressure or water depth from the surface of the sea to the bottom B of the tubular body. For good snorkels V1.times.L1=V2.times.L2, where V1 stands for water-displacement pressure on the top side A of the snorkel, L1 stands for water-exhaust distance to the top end of the snorkel, V2 stands for water-displacement pressure on the bottom side B of the snorkel, L2 stands for water-exhaust distance to the bottom end B of the snorkel; and for bad snorkels V1.times.L1&lt;V2.times.L2 or V1.times.L1&gt;V2.times.L2.
There has been an increasing demand for snorkels which can be adjusted to individual lung capacities or blowing strengths so as to permit the simultaneous water-exhausts from the top and bottom openings of the snorkel.